Process for working up stretched aromatic polyester filaments



Jan. 26, 1965 R. KRETSCH 3,166,886

PROCESS FOR WORKING UP STRETCHED AROMATIC POLYESTER FILAMENTS Filed Jan. 12, 1961 INVENTOR ROSL KRETSCH iw q i. ATTORNEYS United States Patent 3,166,836 PROCEE IS FOR WORKING UP STRETCHED AROMATIC POLYESTER FILAMENTS Rosl Kretsch, Bobingen, near Augsburg, Germany, assignor to Farbwerire Hoeehst'Aktiengesellschaft vormals- Meister Lucius 81 Briining, Frankfurt am Main, Germany, a corporation of Germany Filed Ian. 12, 1961, Ser. No. 82,273 Claims priority, application Germany, Jan. 12, 1960,

8 Claims. in. 57-157 The present invention relates to a process and an apparatus for working up stretched filaments of aromatic polyesters of high molecular weight.

It is known to work up filaments of aromatic polyesters of high molecular weight in a discontinuous manner by twisting the stretched materialand winding it up on a bobbin the core of which consists of, for example, an elastic wire structure. The wound-up filaments are treated on the bobbin for 30 minutes with hot steam at 110 C., whereby setting and shrinkage occurs. Polyester filaments which have been heat-set in the aforesaid manner shrink in boiling water by 0.1 to 0.9% and exhibit a so-called thermo-shrinkage, i.e. a shrinkage in hot air of 200 C. within a few seconds, of 7.0 to 11.0%. After heat-setting, the filaments are wound up on new salable bobbins.

The present invention provides a process and an apparatus which enable stretched polyester filaments to be worked up into a finished salable form in one continuous operation. the stretched filaments are twisted to form a yarn and the yarn is passed through a solutiomdispersion or emulsion of at least one substance boiling between 120 and 350 C. and then fed to twogodets which serveas fixed points and rotate at ditferent speeds and around each of which the yarn is passed several times, the first'of' the godets being heated. Between these godets the-yarn is heated on all sides and uniformly to'a temperature within the range of 220 and 350 C. for 0.1 to 5 seconds, advantageously 0.2 to 1 second, while allowing an adjustable shrinkage of 5 to The yarn thus treated is wound up. All the aforesaid procedures are carried. out in one continuous Working process.

In the process of the invention, the cops with the stretched filaments wound thereon is placed on a spindle rotating at a high speed and the filaments are drawn off atthe head of the spindle and twisted. .The yarn is then introduced via a thread guide and a guide roll into a container which is charged with a solution or emulsion of at least one substance boiling between 120 and 350 C., and then passed several times around an electrically heated godet anclan intermediate roller, the temperature of the godet being adjusted in a manner such that the solvent used, advantageously water, evaporates rapidly from the yarn wrapped around the godet several times. The dried yarnon which only the substances boiling at higher temperature remain behind is treated uniformly and from all sides with hot air of 220 to 350 C., advantageously 250 to 280 C., for 0.1 to 5.0 seconds, advantageously 0.2 to 1 second, whereby the yarn is heatset. For this purpose, the first godet (drying godet) is driven at a higher speed than the unheated godet which serves as second fixed point and is disposed after the zone of hot air. In this mannenthe yarn is allowed to shrink between the two godets in the heating zone by an exactly adjustable amount of 5 to 35%, advantageously 10 to 2 5%. After the yarn has been conductedseveral times around the second godet, it is wound up on a bobbin.

The temperature of the heatable drying godet is within the range of 50 to 120 C.

According to the process of the invention,

. and the esters thereof, .p'olyrnethacry-lic acid, polyvinyl:

The yarns thus obtained are ready for sale and possess very good textile properties. Depending on the conditions of treatment, they have the following textile values: tensile strength between 4.20 and 4.80 g./den., elongation at break between 20 and 35 %,'boiling shrinkage between 0.3 and 2.5%, thermoshrinkage (treatment with hot air at 200C.) between 0.5 and 4.0%. The torsion of the' yarnis excellently set. Contrary to yarns which have beenworked up by the known discontinuous process described in the foregoing, the yarns of the invention contain only an imperceptible proportion of loops and thread ends. Since faults like loops and thread ends are very important as regards the quality'of yarns, this is another great advantage the present process offers in addition to the advantages of a continuous process over a discontinuous one. As will'be shown in Example 2 herein, even filaments which have been considerably damaged during stretching can be worked up by the process of the invention to yield yarns of useful quality. The polyester yarns treated in accordance with the process of the invention can be dyed with dispersion dyestuffs in the absence of carriers and without the application of elevated temperatures to obtain unobjectionable dyeings.

In the process of the invention, the yarn is advan-. tageously passed through a solution, dispersion or emulsion of a substance which can be removed later on by washing or which has thecharacter of a preparation and. is therefore not disturbing if it remains behind in asmall proportion. The chemical nature of the substance is only of minor importance. Decisive are its physical properties. A wide variety of groups of substances maytherefore be used .for carrying out the process of theinvention. The substances shall boil at a temperature between 120 and 350 C.;' at room temperature they may be fluid, sirupy, pasty or may form fiImsQ Crystal line substances of low molecularweight are less suitable for use since they deposit on the-godets. A suitable substance is, for example, sorbitol, a sugar alcohol which is sirupy at room temperature. Besides sugar alcohols there may be used other monoor polyhydric high-boil ing alcohols, for example glycerol and lauryl alcohol, glycols and polyglycols. There may-furthermore advantageously be used'substances containing one. or several they do'not produce yellowing of the filaments on heat-" ing; polymeric compounds, for example polyacrylic acid,

alcohols and esters of polyvinyl alcohols. The solutions, emulsions or dispersions are advantageously prepared with the use of water or an organic solvent boiling be-- lowC.

By adding a dyestuff to the treatment bath, the yarns are simultaneously dyed; By the addition of an optical brightener, for example a substance of the following forthe degree of whiteness oi the yarns is increased. It is also possible to apply a sizing agent to the yarns by adding such sizing agent to the bath. For example, excellently sized yarns are obtained with the use of emulsions of acid polyacrylic acid esters.

An apparatus suitable for use in carrying out the process of this invention is illustrated diagrammatically by way of example in the accompanying drawing.

Referring to the drawing, the apparatus comprises a twisting spindle 1 known in itself and on which the cops 2 carrying the stretched polyester filaments is placed. The apparatus furthermore comprises a thread guide 3 withguide'roll 4,21 container 5 for the treatment bath, which is provided with a pair of immersion. rollers 6, a godet 7 which is provided with a heating means In and to which is allotted an intermediate roller 8, a heating zone 9 (heating chamber or two heated plates situated at a small distance from,.and facing, each other, between which plates the yarn travels, or a flat iron provided with a slit), a second 'godet 10 which is driven and to which belongs an intermediate roller 11, a guide roll 12, a changeable thread guide 13 and a winding-up roller 14.

The following examples serve to illustrate the invention but they are not intended to limit it thereto.

Example 1 were twisted to obtain a yarn 7 having 350 trs./ m. and then passed at room temperature through a bath containing 15% of diphenyl dissolved in ethyl alcohol.

yarn was then fed to a drying godet which was heated to The 80 C. and to which belonged an intermediate roller, the yarn being wrapped 12 times around the godet. The godet was driven at a circumferential speed otso m./ min. The yarn then traveled through a heating chamber which was cm. long and electrically heated to 260 C. The heating chamber was provided on one side with a slit-like opening 2 to 5 mm. wide in which the yarn traveled without touching the hot walls of the chamber. The yarn was then drawn off by the draw godet, around which it was wrapped 12 times, at a speed of 42.5 m./minute so that the yard was allowed to shrink in the heating chamher by 15 After leaving the draw godet, the yarn was wound up.

The yarns so obtained were ready for sale and were of very good quality. They were twisted, heat-set, woundup and entirely free from loops and thread ends. Comparison yarns. which had been made from the same cops but had been first twisted, then heat-set with hot steam on a special bobbin and finally wound up in separate operations possessed poorer textile properties than the yarns prepared according to Example 1.

Example 2 Continuous filaments of polyethylene terephthalate havinga titer of 100/50 were stretched under conditions under which an extremely large amount of loops and thread ends would have been expected to form. Half the cop was worked up as described in Example 1 and the remaining half was worked up discontinuously While otherwise proceeding as described in Example 1. A determination of the formation of loops and thread ends clearly showed that almost no loops and thread ends were formed in the continuous process of the present invention.

Example 3 A cop carrying stretched continuous filaments of polyethylene terephthalate having a titer of 100/ 50 was twisted to obtain 350 trs./m. S-twist and worked up as described in Example 1. The bath contained a 15% aqueous sorbitol solution of room temperature. The drying godet was heated to 100 C. and was surrounded 12 times by the yarn. The speed was 50 m./ min. The heating slit was heated to 260 C. The draw godet around which the yarn was also wrapped 12 times rotated at a speed of 37.5 m./min. so that the yarn was allowed to shrink by 25%. After having left the draw godet, the yarn was wound up on a bobbin.

The yarns could be dyed particularly well with dispersion dyestuils, deep shades being obtained. he yarns were free from loops and thread ends and had the following textile values:

Tensile strength g./den 4.5

Elongation at break a percent 43.8

Capillary loops per 10,000 m. 0

Thread ends per 10,000 m O Shrinkage on boiling "percent" 0.9

I Thermoshrinkage do 0.8

Example 4 Stretched continuous filaments of polyethylene tercphthalate having a titer of 100/50 and which were wound up on a cop were twisted to obtain 350 trs.. m. S twist and worked up as described in Example 1. The treatment bath contained aqueous glycerol of 20% strength (room temperature) and 1% of a dyestufi of the following formula 0 NHQ ll in l L II \J BO: 0 NH;

The drying godet was heated to 100 C. and surrounded 12 times by the yarn. It rotated at a speed of 50 m./ min. The heating chamber was heated to 260 C. The draw godet around which the yarn was also passed 12 times rotated at a speed of 37.5 m./min. so that the yarn was allowed to shrink by 25%. After winding up, yarns of an intense violet color were obtained.

Example 5 Stretched continuous filaments of polyethylene terephthalate having a titer of 100/ 50 and which were wound up on a cop were twisted to obtain 350 trs/min. S twist and worked up as described in Examp.e 1. The bath contained a 15 aqueous emulsion of a partially saponilied polyacrylic acid ester. The drying godet was heated to a temperature of C. and surrounded 12 times by the wetted yarn. It turned at a speed of 50 rn./rnin. The heating slit was heated to 265 C. The draw godet around which the yarn was also passed 12 times rotated at a speed of 42.5 m./min. so that the yarn was allowed to shrink by 15%. The finished yarn was surrounded by a smooth, Well adhering film of sizing agent.

I claim:

1. A process for the working up of stretched filaments of aromatic polyesters of high molecular weight which comprises twisting the stretched filaments to produce a yarn, passing the yarn through a bath consisting of a member selected from the group consisting of a solution, dispersion and an emulsion of at least one substance boiling at a temperature within the range of 120 and 350 C., feeding the yarn to two rotatable means serving as fixed points and rotating at ditferent speeds and around each of which the yarn is wrapped several times, the first rotatable means being electrically heated, heating the yarn between the rotatable means on all sides and uniformly to a temperature within the range of 220 to 350 C. for 0.1 to 5 seconds, simultaneously allowing an adjustable shrinkage of the yarn of 5 to 35% and finally winding up the yarn, all these operations being carried out in one continuous working process.

2. The process of claim 1 wherein the yarn is heated to a temperature within the range of 250 to 280 C.

3. The process of claim 1 wherein the yarn is allowed to undergo an adjustable shrinkage of 10 to 25%.

4. The process of claim 1 wherein the bath consists of a member selected from the group consisting of a monofunctional reactive compound and a polyfunctional reactive compound which reacts at elevated temperature with the filaments of aromatic polyester and thereby improves the dye receptivity of the yarn.

8. The process of claim 1 wherein a sizing agent is additionally added to the bath.

References Cited in the file of this patent UNITED STATES PATENTS 2,381,398 Bosomworth Aug. 7, 1945 2,450,045 Jackson et al Sept. 28, 1948 2,897,863 Schenker Oct. 1, 1957 2,846,752 Lessig Aug; 12, 1958 2,926,065 Coplan et al Feb. 23, 1960 3,079,665 'Saylor Mar. 5, 1963 

1. A PROCESS FOR THE WORKING UP OF STRETCHED FILAMENTS OF AROMATIC POLYESTERS OF HIGH MOLECULAR WEIGHT WHICH COMPRISES TWISTING THE STRETCHED FILAMENTS TO PRODUCE A YARN, PASSING THE YARN THROUGH A BATH CONSISTING OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF A SOLUTION DISPERSION AND AN EMULSION OF AT LEAST ONE SUBSTANCE BOILING AT A TEMPERATURE WITHIN THE RANGE OF 120* AND 350* C., FEEDING THE YARN TO TWO ROTATABLE MEANS SERVING AS FIXED POINTS AND ROTATING AT DIFFERENT SPEEDS AND AROUND EACH OF WHICH THE YARN IS WRAPPED SEVERAL TIMES, THE FIRST ROTATABLE MEANS BEING ELECTRICALLY HEATED, HEATING THE YARN BETWEEN THE ROTATABLE MEANS ON ALL SIDES AND UNIFORMLY TO A TEMPERATURE WITHIN THE RANGE OF 220* TO 350* C. FOR 0.1 TO 5 SECONDS, SIMULTANEOUSLY ALLOWING AN ADJUSTABLE SHRINKAGE OF THE YARN OF 5 TO 35% AND FINALLY WINDING UP THE YARN, ALL THESE OPERATIONS BEING CARRIED OUT IN ONE CONTINUOUS WORKING PROCESS. 